Autism schools in Gloucestershire

My husband and I are moving back to Gloucestershire (most likely Cheltenham/Tewksbury area.) We have a ten year old son who is autistic, he's currently in a special education school with children of mixed abilities. We are looking for a school in Gloucestershire that either has a specialist unit or specializes in HFA. He has sensory issues and needs to be in quiet fairly small, environment but does well academically when the conditions are right. We have the flexibility to move to an area where his educational needs can be met, does anyone have any suggestions?